Quick Summary
- The RCCT measures the function of your red, green, and blue cone cells separately, one eye at a time.
- The test uses colored letters that fade in contrast until you can no longer identify them, which produces a score for each cone type.
- Subtle changes in cone function can appear with glaucoma, diabetic eye disease, and age-related macular degeneration.
- Our doctors use the RCCT alongside OCT, ERG, and visual field testing for early and thorough disease detection.
- The diagnostic RCCT is billed to medical insurance. The FAA color vision test for pilots is $150 and is not covered by insurance.
What Is the Rabin Cone Contrast Test?
The RCCT does more than identify color blindness. It assigns a separate score to each type of cone cell, so your doctor can see which part of your color vision system is changing and by how much. These scores create a measurable baseline that future results can be compared against to track whether your color vision is stable or shifting over time.
Where the Test Came From
The test is named for vision scientist Dr. Jeffrey Rabin, whose research on cone-specific color vision dates back to the 1990s. His early work showed that measuring each cone type separately could identify both the type and the severity of a color deficiency. In 2011, Rabin and colleagues published research describing a rapid, computer-based version of the cone contrast test, and it was later adopted by the U.S. military for screening pilots.
How Your Cone Cells Work
Your retina contains two main types of light-sensing cells: rods and cones. Rods help you see in dim light, while cones handle color vision and sharp, detailed central vision. There are three types of cones, and each responds best to a different range of light:
- L cones (long wavelength): Most sensitive to red light
- M cones (medium wavelength): Most sensitive to green light
- S cones (short wavelength): Most sensitive to blue light
Your brain blends the signals from all three cone types to create the full range of colors you see. S cones are far less numerous than L and M cones, which is one reason the blue portion of the RCCT uses larger, higher-contrast letters. When disease affects the retina or optic nerve, one cone type may begin to lose sensitivity before you notice any change in your everyday vision.
How the RCCT Works During Your Visit
The RCCT is quick, comfortable, and noninvasive, with no eye drops or contact with your eye. Published reports describe the test as taking about three minutes per eye. Here is what the process looks like:
- You sit in front of a calibrated screen and cover one eye.
- Colored letters appear one at a time against a gray background. Each letter is designed to be visible to only one cone type.
- You identify each letter as it appears.
- The letters gradually become fainter until you reach your threshold, the point at which you can no longer identify them.
- The process repeats for each cone type and then for the other eye.
The software converts your responses into a score for each cone type in each eye. These scores are placed on a 100-point scale, which makes results easy for your doctor to compare from one visit to the next.
How the RCCT Compares to Traditional Color Plate Tests
Traditional color vision screening asks you to pick out numbers hidden in colored dot patterns. These plates remain a helpful screening tool for inherited color deficiencies, but they offer less detail about how much function each cone type has. The RCCT measures each cone type, which allows your doctor to detect smaller changes.
The RCCT letters are also presented at a size well above the 20/20 line. This helps keep the score focused on color sensitivity rather than on how sharply you see. Focusing issues such as nearsightedness or astigmatism are less likely to influence the result, although your doctor may still ask you to wear your glasses or contacts during the test.
Why the RCCT Helps Detect Eye Disease Early
Many eye diseases damage the retina or optic nerve gradually, often while your vision on a standard eye chart still looks normal. Small changes in how your cones respond to color and contrast can appear before you notice anything is wrong. The RCCT is highly sensitive to these subtle changes, which gives you and your doctor more time to monitor the condition and begin treatment when it can do the most good. You can learn more about many of these diseases in our article on common eye conditions explained.
Glaucoma
Glaucoma damages the optic nerve and often develops without symptoms until significant vision has been lost. Researchers have used the RCCT to study acquired color vision changes in people with glaucoma, and reduced cone contrast scores have been documented in patients with the disease. For patients who come to us for glaucoma testing from across the Asheville, NC area, the RCCT adds a functional measurement to the structural information gathered through other tests.
Diabetic Eye Disease
Diabetes can affect the retina well before visible signs of diabetic retinopathy appear during an exam. Several studies have found that the blue-sensitive S cone pathway is especially vulnerable in people with diabetes, including some who show no retinopathy at all. Because the RCCT measures S cone function on its own, it can help your doctor watch for these early changes. Our page on diabetes and your eyes explains more about how diabetes affects vision.
Age-Related Macular Degeneration
Age-related macular degeneration (AMD) affects the macula, the area of the retina packed with cone cells that is responsible for sharp central vision. For AMD, our doctors use OCT, the Rabin color test, and the RETeval ERG as more specialized testing.
How the RCCT Fits With Our Other Testing
The RCCT measures how well your cones are functioning, while other tests show the physical structure of your eye or how the retina responds to light. At our practice, the RCCT is used alongside these tests:
- Optical Coherence Tomography (OCT): Takes cross-sectional images of the retina using a scanning laser
- Electroretinography (ERG): Measures the electrical response of the retina to light
- Visual Field Testing: Checks for blind spots in your peripheral, or side, vision
Combining functional and structural testing gives our doctors the most complete picture possible. You can read more about the full range of diagnostic tools on our medical testing page and our vision technology page.
FAA Color Vision Testing for Pilots
Along with the diagnostic RCCT, we offer the specific version of the test approved by the Federal Aviation Administration. This option is available for student pilots seeking a medical certificate and for pilots who need follow-up color vision testing.
According to the FAA's Guide for Aviation Medical Examiners, pilot color vision testing must use an approved computer-based test as of January 1, 2025, and the testing must be done in person. The RCCT is on the FAA's list of approved tests. Key requirements for the RCCT include:
- The Air Force/Army/Navy/Coast Guard version of the test must be used.
- Each eye is tested separately.
- A score of 55 or higher is required for each color.
The FAA color vision test at our office costs $150 and is not covered by insurance. Before scheduling, we recommend checking with your Aviation Medical Examiner about how your results should be provided for your medical certification. Pilots in the Asheville area and across western North Carolina can complete this testing at our Arden office.
Who Should Consider the RCCT
Your doctor will recommend the RCCT based on your health history and exam findings. Our practice uses the RCCT for patients with any eye disease, including:
- Glaucoma or suspected glaucoma
- Diabetes, with or without signs of diabetic retinopathy
- Age-related macular degeneration
- Other eye diseases that can affect the retina or optic nerve
- Pilots and student pilots who need FAA color vision testing
If you fall into one of these groups, ask about the RCCT at your next comprehensive eye exam.
Insurance and Cost
The diagnostic RCCT is billed to your medical insurance because it is used to evaluate and manage eye disease. Coverage varies by plan, and our team can help you understand your benefits. Visit our insurance page for more information about the plans we work with.
The FAA color vision test is a separate service. It costs $150 out of pocket and is not covered by insurance.
Frequently Asked Questions
Is the Rabin Cone Contrast Test painful?
No. The RCCT is completely noninvasive. You simply look at a screen and identify letters as they appear. There are no eye drops or physical contact with your eye.
How long does the RCCT take?
The test takes about three minutes per eye. Your total visit time depends on the other tests your doctor performs.
Is the RCCT the same as a color blindness test?
The RCCT can detect inherited color deficiencies, but it does much more than that. It measures the function of each cone type separately, which allows your doctor to identify subtle changes caused by eye disease and track them over time.
Can the RCCT diagnose glaucoma or diabetic retinopathy on its own?
No single test diagnoses these conditions alone. The RCCT provides important functional information, and your doctor combines it with OCT, ERG, visual field testing, and a thorough eye exam to reach a diagnosis and guide treatment.
Take the Next Step in Protecting Your Vision
The Rabin Cone Contrast Test gives our doctors a precise, measurable look at how your cone cells are working. For patients with glaucoma, diabetes, or macular degeneration, this information can reveal changes early and support more informed care. For pilots, it offers a convenient way to complete FAA color vision testing close to home.
Our experienced doctors are ready to answer your questions and help you decide whether the RCCT is right for you. Schedule your appointment online or contact our Arden office to learn more.